This invention relates to he fabrication of a liquid-fueled rocket engine, and, more particularly, to the attachment of the injector to the combustion chamber.
A typical liquid-fueled rocket engine includes a generally cylindrical combustion chamber, with an injector attached to its injector end and a flared nozzle attached to its nozzle end A liquid propellant including fuel and an oxidizer flows through injector ports in the injector and into the combustion chamber. The propellant is mixed and ignited in the combustion chamber. The hot gas resulting from the combustion expands through the nozzle and drives the rocket eggine and the attached rocket structure in the direction opposite to that in which the nozzle is pointed.
In order to achieve maximum efficiency of the rocket engine in terms of thrust per weight of propellant and maximum specific impulse, the mixing (if any) of the propellant components must be complete to encourage complete combustion. An internal step structure at the injector end of the combustion chamber is under development to promote the complete mixing and combustion. The step structure also protects the injector end of the combustion chamber wall from the highest of the tp es developed inside of the combustion chamber.
The injector is normally welded or bolted to the injector end of the combustion chamber to achieve two main objectives, structural attachment and sealing against leakage of hot gas during engine firing. However, because of the high heating rates and thermal expansion mismatches associated with the rocket engine having a step strucre, welding and bolting have not proved feasible with this combination of different materials. A more complex attachment structure involving several different materials is required at the injector end.
Thus, while the rocket engine with internal step structure in the combustion chamber offers important potential benefits in terms of improved efficiency and specific impulse, those benefits have not been fully realized in initial forms of the rocket engine in part because of fabrication difficulties. There is a need for a fabrication approach which provides the necessary strength and sealing against hot gas leakage, and also allows the step design to function without damaging the combustion chamber. The present invention fulfills this need, and further provides related advantages.